The present invention is directed to an apparatus for wrapping packages in heat-sealable wrapping materials, such as polypropylene film, and the like. The apparatus of the present invention has particular application to the wrapping of baked goods, such as bread, rolls, and the like. The present invention is an improvement on what is conventionally called a "L-sealer" machine currently in widespread use. The "L-sealer" machine comprises a pivotal, downwardly movable, heat-sealing and cutting pressure frame which includes a pair of electrically conductive wires arranged perpendicularly to each other to form an L-shape, which wires seal the plastic film thereunder upon pressure applied to the moveable frame, such that the transverse conductive wire cuts the plastic film into two distinct portions while, at the same time, forming a seal at each adjoining and severed portion of the plastic film. This provides a sealed edge for the plastic film in which is provided baked goods, and the like, while the upstream plastic film portion is sealed at that portion that will constitute the bottom or leading edge of the bag next-to-be-formed. Examples of the conventional L-sealer apparatus for forming a completely sealed plastic bag are disclosed in U.S. Pat. Nos. 3,135,077; 3,239,993; 3,323,282; and 3,214,884.
Conventional plastic film, bag-forming apparatuses of the L-sealer type feed plastic film over a roll with doubled-over plastic film. The doubled-over film is fed to a forming station and under the pivotal and downwardly movable pressure frame incorporating the L-seal arranged electrically-conductive wires. While at this location, the contents, such as baked goods, are placed in the plastic film between the doubled-over layers, and thereafter the pressure frame is pivoted downwardly and pressed to provide a seal for the two unsealed side edges via the pair of electrically-conductive wires. After the bag has been sealed, so that it is sealed around its entire circumference, it is removed and the previously sealed lead-end of the roll of plastic film is advanced to provide the next bag for wrapping the contents. During heat sealing by the two electrically conductive wires, both the trailing edge of the bag being formed and the leading edge of the next bag to be formed are sealed simultaneously via the transverse electrically-conductive wire generally extending perpendicularly to the path of travel of the plastic film. Conventional L-sealer packaging machines, as explained above, form a completely sealed bag with no open sides, which do not allow access to the interior of the bag without first destroying one of the closed sides thereof. Thus, when a consumer purchases the contents of the bag, he must tear open the bag in order to access the contents, thus destroying that bag for further use in storing the contents, since, upon opening the bag, at least one side has been destroyed and is not capable of being reclosed by the consumer in a manner assuring continued freshness to the contents.
It is the object of the present invention to provide an apparatus that forms a bag sealed and closed along only three of its sides, with the fourth side thereof constituting a top end that is left open and unsealed after the heat-sealing process. The open unsealed side may then be subsequently closed off via a twist-tie type of closure element, or the like, in order to allow the consumer to reuse the bag more than once, since the bag had not been destroyed upon being opened.